Retainer clip for brake-pad support pins

ABSTRACT

A retainer clip for brake-pad support pins of vehicle brake calipers, is provided, wherein at least one support pin that is supported removably by a caliper element, which is intended to hold the pads, and which has a safety device associated removably with the support pin to prevent the support pin from slipping out of the caliper element. The retainer clip has, for each support pin, a respective clip with an eye which can be mounted astride the support pin, wherein the eye extends around the support pin, the support pin having abutment means, for example, a larger diameter and a smaller diameter, for preventing relative axial sliding of the clip on the support pin in at least one direction, thereby preventing slipping of the support pin out of the caliper element.

FIELD OF THE INVENTION

The present invention relates in general to brakes and, moreparticularly, to disk brakes, particularly but not exclusively forvehicles. More specifically, the invention relates to a safety devicefor brake-pad support pins or bolts.

BACKGROUND INFORMATION

In disk brakes, particularly of the type fitted in vehicles, the padswhich bear linings of friction material are supported within a so-calledcaliper body with the ability to move away from and towards the disksurface or braking band when they are acted on by hydraulic or pneumaticcylinder-piston units so as to be able to perform the braking actionwhen required. Pins or bolts are used for supporting the pads in thecaliper body and extend through the caliper body and throughthrough-holes provided in the pads, their ends engaging in seatsprovided for the purpose in the caliper body. These support pins aresupported by the caliper body so as to be removable axially since theyhave to be removed to enable the pads to be replaced when they are worn.However, the pins must be prevented from slipping out of the caliperbody accidentally when the vehicle is in motion since this would resultin the correct operative positioning of the pads no longer beingensured.

According to a known solution, the pins supporting the pads areprevented from slipping out of the caliper body by means of safety splitpins mounted substantially in the vicinity of one end of each supportpin, each split pin having a first limb which can be fitted in athrough-hole formed for the purpose in the support pin, transverse theaxis thereof. The other limb of each split pin has a portion which isshaped to form an arc with a radius substantially corresponding to thatof the support pin and which grips the support pin, when the split pinis mounted, to prevent the first limb from undesirably slipping out ofthe through-hole in the support pin.

Moreover, the caliper body has recesses which leave the support pinsexposed in the region of the transverse through-holes formed therein andthe split pins are housed in these recesses. The split pins thus comeinto abutment with the walls of the recesses, preventing the supportpins from slipping out.

Clearly, once the split pins are fitted in the respective support pins,they are also fixed for rotation with the support pins about the axesthereof. When the vehicle is in motion and, in particular, each timebraking takes place, vibrations are produced and are propagated to thepins supporting the pads. These support pins, which are housedsubstantially loosely in the caliper body, vibrate and tend to rotateabout their own axes, also causing the respective split pins to rotate.

To prevent the rotation of the support pins causing the split pins tostrike against portions of the caliper body, for example, against theedges of the recesses housing the split pins, the eyes of the split pinsare bent so as to lie in a plane perpendicular to the plane in whichtheir two limbs lie. When the split pins are fitted, their eyes thus liesubstantially on an outer surface of the caliper body in the vicinity ofthe edges of the respective recesses.

This solution may have disadvantages since the rotations of the supportpin about its own axis are transmitted to the split pins, causing themto knock or at least rub against the caliper body. In time, the splitpins could deteriorate or break. Any breakage of the split pins is anevent which could have disastrous consequences and is absolutely to beavoided.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a safetydevice for brake-pad support pins which does not have theabove-mentioned disadvantages.

According to the present invention, this object has been achieved by aretainer clip for brake-pad support pins. In one embodiment, thebrake-pad support pin is supported removably by a caliper element whichis intended to hold the pads. The retainer clip is associated removablywith at least one support pin to prevent the support pin from slippingout of the caliper element. The retainer clip of this embodimentcomprises, for each support pin, at least one respective clip with aneye which can be mounted astride the support pin wherein the eye extendsaround the support pin, and in that the at least one support pin hasabutment means for preventing relative axial sliding of the clip on thesupport pin in at least one direction, preventing slipping of thesupport pin out of the caliper element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an elevational view of a retainer clip as one embodiment ofthe invention.

FIG. 2 illustrates the cross section through the safety pin taken in theplane II—II of FIG. 1.

FIG. 3 illustrates a plan view of a vehicle disk-brake caliper accordingto one embodiment of the invention.

FIG. 4 shows an elevational view of a detail of the caliper of FIG. 3,showing the stages of the fitting of the safety pin, and

FIG. 5 illustrates a cross section taken in the plane V—V of FIG. 4.

DETAILED DESCRIPTION

FIGS. 1 and 2 show, in an elevational view, and in a section taken inthe plane II—II of FIG. 1, respectively, a retainer clip 1 forming partof a safety device according to a possible embodiment of the presentinvention. The retainer clip 1 is made of a metal wire suitably formedin the manner shown by the figures.

The metal wire of the embodiment shown in FIGS. 1 and 2 may be a wiremade of steel, for example stainless steel and even more specificallyAISI 302 steel. The metal wire of this embodiment has a circularcross-section of substantially uniform diameter along its length. Thediameter of the steel wire is, for example, approximately 1.2 mm.

The retainer clip of this embodiment comprises a substantially straightcentral portion 2 of length L1. According to one embodiment, the lengthL1 of the central portion 2 is predominant compared to the overalllength of the retainer clip. The central portion 2 has, at its two ends,two wide bends 3, the two wide bends having a radius of curvature, forexample, of about 8 mm, and connect the central portion 2 to two lobes 4which act as clips. The length L1 of the central portion is, forexample, about 88-89 mm, although this value is given purely by way ofexample and may vary from one case to another according to the distancebetween the elements (for example, the interaxial spacing between thebrake-pad support pins, as will become clear from the following) onwhich the safety pin is to be mounted.

Each lobe 4 of this embodiment comprises a first limb 5 and a secondlimb 6 coplanar with the central portion 2 and perpendicular thereto,the first and second limbs 5, 6 being of substantially equal length andsignificantly shorter than the central portion, and being spaced apartby a distance D1, for example, about 14 mm. The wire constituting theretainer clip is formed, between the first limb and the second limb in asubstantially “Ω”-shaped, reentrant loop 7, referred to herein as aneye, which has a narrow opening 8 also referred to herein as anaperture, having an aperture opening length D2 and then the eye widensout into a circular portion 9 having an inside diameter D3, wherein theinside diameter is greater than the aperture opening length. Forexample, in one embodiment the aperture opening length D2 is about 3 mm,and the inside diameter D3 of the circular portion 9 is about 4.6 mm. Asalready stated for the central portion length L1, the inside diameterand the aperture opening length may be selected according to thedimensions of the elements on which the safety pin is to be mounted.

The end of the second limb 6 of this embodiment of each clip 4 is bentand extends towards the first limb 5 forming an appendage 10, which canbe gripped manually or by means of a tool and which is inclined slightlytowards the eye 7 so as to prevent the end of the metal wire fromprojecting dangerously.

The clip-like behaviour of the lobes 4 is made possible by the resilientbehaviour of the metal wire of the retainer clip of this embodiment and,in particular, by the ability of the circular portion 9 to bend understress and to become wider, and of the limbs 6 to bend and/or to beinclined, under stress, towards the respective adjacent limbs 5, so asto bring about a temporary widening of the apertures D2 of the narrowerportions 8 and then to return resiliently to the rest position when thestress is removed. The stress may be a stress applied directly to thenarrower portions 8 by forcing the retainer clip 1 astride the elements,such as the support pin or bolt, which are to be prevented from slippingout. In the case of forcing the retainer clip onto a support pin, thecircular portions 9 bend and widen and the limbs 6 are inclined towardsthe respective limbs 5. Alternatively, the stress may be a stressapplied to the ends of the limbs 6, for example, by pulling on theappendages 10, as occurs when the safety pin is to be removed from theelements, for example, to allow them to slip out; in this case, thelimbs 6 bend and are inclined towards the respective limbs 5 and thecircular portion 9 in turn bends, bringing about a temporary widening ofthe narrower portion 8. Clearly, the resiliency or flexibility of thelobes 4 depends on a combination of factors, amongst which are theparticular material of which the metal wire, the diameter of the metalwire, the inner diameter of the circular portion 9 of the eye of thelobes 4, and other factors known to one of ordinary skill in the art.More specifically, once the material to be used and the minimum desired“extraction load” (that is, the tensile force to be exerted on thesafety pin in order to disconnect the clips 4 from the elements on whichthey are mounted) has been established, the principal dimensions of theclips 4 will consequently be determined. The values provided by way ofexample in this embodiment are suitable for ensuring a minimumextraction load of about 20 N, for a retainer clip made of AISI 302steel having a diameter of the metal wire of 1.2 mm.

FIG. 3 shows an embodiment of a vehicle disk-brake caliper in a planview. The caliper comprises a caliper body 30, which, in the embodimentshown, is formed by two juxtaposed half-bodies 31 and 32 fastenedtogether by screws 33, but which could alternatively be constituted by asingle element. The caliper body extends astride a portion of a brakingband of a disk 34, which is shown schematically. Seats 100 are formed inthe caliper body 30 for housing two brake pads 35 of friction materialdisposed on either side of the disk 34. Each brake pad 35 comprises aplate 36 supporting a lining 37 of friction material facing towards thebraking band of the disk 34. The pads are fastened and positioned in thecorrect operative positions in the respective seats by support meanssuch as support pins or bolts.

Cylinder-piston pairs operated, for example, hydraulically, are formedin the two half-bodies 31 and 32, in known manner, in order to urge thepads 35 towards the two sides of the braking band of the disk 34 so thatthe linings 37 of friction material come into contact with the brakingband. In FIG. 3, four cylinder-piston pairs 50, that is, two for eachhalf-body 31, 32, are shown schematically.

The means for supporting the pads 35 comprise a pair of support pins orbolts 38 which are arranged transversely relative to the caliper bodyand the opposed ends 39, 40 of which are held by being fittedsubstantially loosely in respective seats provided in the caliper body30. In a specific embodiment, on the side formed by the half-body 31,the seats for the ends of the support pins 38 are two blind holes or,alternatively, through-holes with stop abutments for the support pins,and on the side formed by the half-body 32, two through-holes 46 areformed in a shoulder 45 of the half-body 32. The support pins 38 extendthrough throughholes 41 provided for the purpose in the plates 36 of thepads 35, thus supporting the pads 35 and ensuring their correctoperative positioning. A cross-shaped spring 42 comprises a springportion 420 which extends longitudinally relative to the caliper body 30and a spring portion 421 arranged transversely relative to the springportion 420 and operatively connected, for example riveted, thereto. Thespring portion 421 urges the pads 35 away from the disk 34, that is,towards the respective cylinder-piston units 50 so that, when thebraking action is not exerted, the pads are forced away from the brakingband by the springs. The two ends 44 of the cross-shaped spring 42, onthe other hand, extend beneath the two support pins 38.

Two recesses 47 formed in the shoulder 45 of the half-body 32 on theside facing inwardly, that is, towards the pads 35, in the region of thethrough-holes 46, are open on the side facing towards the pads 35. Thetwo recesses 47 can house the two lobes 4 of the retainer clip 1 afterthe retainer clip 1 has been mounted astride the two support pins 38.The central portion 2 of the retainer clip 1 extends between the twosupport pins 38, remaining slightly above the shoulder 45 of thehalf-body 32. It can be seen that, although in the embodiment shown thetwo recesses 47 are open towards the pads 35, these recesses couldalternatively be formed as open-topped grooves, closed at the bottom andat the sides, and wide enough to allow the lobes of the retainer clip tobe inserted.

With reference to the embodiment illustrated by FIGS. 4 and 5, thesupport pins 38 each have peripheral grooves 48 in the vicinity of theirends 40. In one possible embodiment, the safety pins have a peripheralgroove diameter slightly greater than the inside diameter D3 of thecircular portion 9 of the eye 7, and the peripheral groove diameter issmaller than the outer diameter of the support pins 38, wherein once theclips 4 have been mounted astride the support pins 38 in the region oftheir grooves 48, there is slight force applied by the eyes 7 on thesupport pins. In an alternative embodiment, the safety pins have aperipheral groove diameter that is slightly less than the insidediameter D3 of the circular portion 9 of the eye 7 such that the lobes 4are mounted astride the grooves 48 of the support pins 38 with a slightclearance between the peripheral grooves and the lobes. The apertureopening distance D2 of the narrow opening 8 is less than the peripheralgroove diameter of the support pins 38 wherein the lobes 4 of theretainer clip do not slip off the support pins 38 accidentally once theyhave been mounted thereon. The values given above by way of example forthe most important dimensions of the retainer clip are suitable for usewith support pins having a maximum diameter of at least approximately 6mm and a diameter in the grooves 48 of about 4.7-4.8 mm, and relate to asituation in which the safety pins are required to be mounted astridethe support pins with a slight force applied by the eyes on the supportpins. It may be clear to one of ordinary skill in the art that thedimensions of the retainer clip may be modified to adapt them to supportpins of different diameters.

In order to mount the retainer clip, it suffices to proceed as shownschematically in FIG. 4, by positioning the retainer clip so that theeyes 7 are disposed adjacent the grooves 48 of the support pins and thento push the retainer clip onto the support pins 38 so that the apertureopening distance D2 of the narrow openings 8 are widened sufficiently,owing to bending of the circular portions 9 of the eyes 7, for thesupport pins to pass through the narrow openings 8 and to snap into thecircular portions 9 of the eyes 7. The lobes 4 are thus mounted astridethe support pins 38.

When the retainer clip is mounted astride the support pins 38, thesupport pins 38 are prevented from slipping out of their seats in thecaliper body and the support of the pads 35 is thus ensured. However,since in one embodiment the eyes 7 of the retainer clip apply a slightforce to the support pins 38, or in an alternative embodiment have aslight clearance between the peripheral grooves and the lobes, thesupport pins 38 may rotate as a result of vibrations generated when thevehicle is in motion, and especially during braking, without unavoidablyresulting in rotation of the retainer clip 1 which is not fixed relativeto the support pins but merely restrains them from slipping out axially.The fact that the support pins can rotate without the retainer cliprotating means that the retainer clip is not subjected to repeatedknocking against the caliper body or other parts of the brake and istherefore not subject to breakages over time. This is also due to thefact that the retainer clip extends astride and is mounted on both ofthe support pins.

In order to remove the retainer clip, for example, when the pads 35 needto be replaced, it suffices to exert a pull on the appendages 10 of thesafety pin until the eyes 7 of the safety pin snap out of grooves 48 ofthe respective support pins 38. Alternatively, one can, at the sametime, push the second limb 6 towards the first limb 5 so as to bend thecircular portions 9, consequently widening the aperture opening diameterD2 of the narrow opening 8 of the eyes 7.

In the foregoing description, a so-called fixed caliper is referred topurely by way of example. Clearly the present invention may also beapplied to calipers of other kinds, for example, to so-called floatingcalipers, in which at least one bolt or pin is nevertheless used forsupporting the pads; these may either be calipers of the type having asupport for housing the pads which is separate from but operativelyconnected to an actual caliper body, or of the type which does not havesuch a separate support.

Similarly, the invention is also applicable when the number of pinssupporting the pads is other than two, possibly even when there is onlyone support pin.

Naturally, variants and or additions may be applied to the embodimentdescribed and illustrated above without thereby departing from the scopeof protection defined in the appended claims.

What is claimed is:
 1. A retainer clip for brake-pad support pins ofvehicle brake calipers, the support pins each having a structuralabutment, the retainer clip comprising: a central portion havingopposite ends; at least two wide bends; at least two lobes, wherein theat least two lobes are connected to the opposite ends of the centralportion by the at least two wide bends, and wherein the central portion,the at least two wide bends, and the at least two lobes are formed froma single metal wire, and wherein each of the at least two lobesincludes: a first limb connected to one of the at least two wide bends;a second limb; and an eye, wherein the eye connects the first limb tothe second limb, and wherein the eye is formed with a narrow openinghaving an aperture opening distance, and a circular portion having aninner diameter, wherein the aperture opening distance is less than theinner diameter of the circular portion, and wherein the inner diameterof the circular portion of each of the at least two lobes is less thanthe size of the structural abutment, wherein each of the at least twolobes abuts the structural abutment of the respective support pin,thereby preventing relative axial sliding in at least one directionbetween the retainer clip and the support pins.
 2. A retainer clipaccording to claim 1, wherein the structural abutment of each of thesupport pins comprises a larger portion with a larger diameter and asmaller portion with a smaller diameter, wherein the inner diameter ofthe circular portion is less than the larger diameter of the supportpins, and wherein, when the retainer clip is mounted on the supportpins, the at least two lobes are mounted astride the support pins at thesmaller portion of the support pins, and wherein the larger portion ofthe support pins abuts the at least two lobes, thereby preventingrelative axial sliding in at least one direction between the retainerclip and the support pins.
 3. A retainer clip according to claim 2,wherein the inner diameter of the circular portion of the at least twolobes is slightly less than the smaller diameter of the support pins,wherein there is a slight force applied by the eyes of the at least twolobes on the support pins, when mounted, and wherein the metal wire isresilient, allowing the aperture opening distance to be widenedresiliently during mounting of the retainer clip on the support pins andduring removing of the retainer clip from the support pins.
 4. Aretainer clip according to claim 3, wherein the second limb of each ofthe at least two lobes terminates in an appendage that can be acted onto resiliently widen the aperture opening distance.
 5. A retainer clipaccording to claim 2, wherein the inner diameter of the circular portionof the at least two lobes is slightly greater than the smaller diameterof the smaller portion of the support pins whereby there is clearancebetween the eyes of the at least two lobes and the smaller portion ofthe support pins, and wherein the aperture opening distance of thenarrow opening is less than the smaller diameter of the support pins,and wherein the metal wire is resilient, thereby allowing the apertureopening distance to be widened resiliently during mounting of theretainer clip on the support pins and during removing of the retainerclip from the support pins.
 6. A retainer clip according to claim 5,wherein the second limb of each of the at least two lobes terminates inan appendage that can be acted on to resiliently widen the apertureopening distance.
 7. A vehicle brake caliper for a disk brake includingthe retainer clip of claim
 2. 8. The vehicle brake caliper according toclaim 7, wherein the inner diameter of the circular portion of the atleast two lobes of the retainer clip is slightly less than the smallerdiameter of the support pins, when mounted, wherein there is a slightforce applied by the eyes of the at least two lobes on the support pins,and wherein the metal wire is resilient, allowing the aperture openingdistance to be widened resiliently during mounting of the retainer clipon the support pins and during removing of the retainer clip from thesupport pins.
 9. The vehicle brake caliper according to claim 7, whereinthe inner diameter of the circular portion of the at least two lobes isslightly greater than the smaller diameter of the smaller portion of thesupport pins whereby there is clearance between the eyes of the at leasttwo lobes and the smaller portion of the support pins, and wherein theaperture opening distance of the narrow opening is less than the smallerdiameter of the support pins, and wherein the metal wire is resilient,thereby allowing the aperture opening distance to be widened resilientlyduring mounting of the retainer clip on the support pins and duringremoving of the retainer clip from the support pins.
 10. A retainer clipaccording to claim 2, wherein the vehicle brake calipers have at leastone structural wall, wherein the retainer clip, in cooperation with theat least one wall of the vehicle brake calipers, prevents the supportpins from slipping out of the vehicle brake calipers.
 11. A retainerclip according to claim 2, wherein the smaller portion of each of thesupport pins comprises a peripheral groove.
 12. A retainer clipaccording to claim 11, wherein the vehicle brake calipers have at leastone structural wall, wherein the retainer clip, in cooperation with theat least one wall of the vehicle brake calipers, prevents the supportpins from slipping out of the vehicle brake calipers.
 13. A retainerclip according to claim 1, wherein the vehicle brake calipers have atleast one structural wall, wherein the retainer clip, in cooperationwith the at least one wall of the vehicle brake calipers, prevents thesupport pins from slipping out of the vehicle brake calipers.
 14. Avehicle brake caliper for a disk brake including the retainer clip ofclaim 1.